Aircraft construction



June 13,1944. q. W.' VERBEKE Y 2,351,284 l IRCRAFT CONSTRUCTION y FiledMay 29.' 1940 5 sheets-snet 1 AQ @ff 4 y `a June 13, 1944. J. w.ovx-:RBEKE AIRCRAFT CONSTRUCTION Filed May 29. 1940 5 Sheets-Sheet 2June 13, 1944. J. w. ovERBEKE AIRCRAFT CONSTRUCTION Filed May 29, 1940 5Sheets-Sheet 3 Jkn milf/'a verfe fie,

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AIRCRAFT CONSTRUCTION Filed May :29,4 1940 5 sheets-sheet 4 @M JM June13, 1944.

J. W. OVERBEKE AIRCRAFT CONSTRUCTION Filed May 29,- 1940 Y 5Sheetsv-Sheet ...llllllllllll Patentetl June 13, 1944 UNITED sTATEsPATENT oEFicE 2,351,284 a AIRCRAFT CONSTRUCTION John 'W. O'verbeke,Anneslie, Md., assigner to The Glenn L. Martin Company, Baltimore, Md.

Application `May 29, 1940, Serial No. 337,818 I 4\ Claims.

` This invention is directed to the construction of means for lockinglanding gear for aircraft in either the up retracted position, or thedown landing position. f

In retractable landing gear for aircraft, it is customary to providesome means for locking the landing gear in either up`(retracted)'position, or down (landing) position. This is' to prevent the landinggear from unexpectedly moving from either one or the other of thesepositions. In the provision of such locking means it is desirable tohave a locking system which is simple of operation, dependable, and ofpositive action. It is also desirable. to have the action of the lockingmechanism which, through failure, does not prevent the landing gear frombeing moved to nal position. l

It is an object of this invention to provide a hydraulically controlledsystem for the locking of the landing gear of an aircraft in either upor down position. l

Another object of the invention is to provide a hydraulically controlledlocking mechanism, the operation of which is in part dependent upon themovement of the landing gear so that the landing gear is always movableto nal position.

Another object of the invention is to provide novel locking connectionsbetween the landing gear and the locking mechanism.

Generally these objects of the invention are obtained by providing ahydraulically operated lock in connection with a novel hydraulic systemwhich is connected either in parallel or in series with thehydraulically operated ing or lowering the landing gear.

The locking mechanism is such that a part of the operation thereof, forunlocking, is dependent upon the hydraulic power provided from thehydraulic systeem, while the locking function is obtained by contact ofthe landing gear with the locking mechanism. The apparatus may havemechanism for raismechanism which can be used in Fig. 1 as illusthe.form in which a trolley portion of the retracting mechanism rides alonga. track and is engaged by locks at either end of the trackcorresponding to the upY and down positions of the gear, or theinventionmay be inthe form of a locking mechanism which engages with a portion ofthe landing gear strut when the strut is moved to either the up or downposition of the landing gear.

The means by which the objects of this invention may be obtained aremore fully described in the accompanying drawings which forma parthereof. In the drawings:

Fig. 1 is a diagrammatic View of a locking systrated on the right-handside thereof.

Fig. 4 is a sectional view-on the line -4-4 of Fig. 3.

Fig. 5 is an enlarged detail of the form of lock shown in Figs. 3 and 4,in inoperative position.

Fig. 6 is amodied form of the locking mechanism usable as shown on theleft-hand side of Fig. 1.

Fig. 7 is a diagrammatic view showing a strut lock mechanism.

Fig. 8 is a side elevational view, partly in section, of the form oflock used'with the mechanism of Fig. '7.

- Fig. 9 is a sectional View on the line 9-9 of Fig. 8.

Fig. 10 is a side elevational view, partly in section, of a modiiledlocking mechanism of the strut .lock type. Fig. 11 is a cross-sectionalview on the line H-I l, Fig. 10.

Fig. 12 is a plan view cfa detail of Fig. 10.

Figs. 1 and 2 `illustrate thetwo diierent types of hydraulic systemswhich can be used to operatethe locking mechanisms of this invention.'I'he illustration is with respect to the so-called trolley i lockingmechanisms of Figs. 3 to 6, but it is understood that the same systemscan be used 'with the so-called strut type locking mechanismsillustrated in Figs. 'I to 1 2, inclusive. In Fig. 1, the hydraulicretracting gear and the hydraulic locking gear are shown connected inparallel with a hydraulic pressure line. Landing wheel 2 is rotatableabout'the axis 4 through movement of the strut '6. This strut isconnected at its upper end f to a trolley `Il movably mounted upon trackI0. Trolley 8 is alsc connected to a driving arm I2, which' arm isoperated by a connecting rod I4 Joined to a piston I6 mounted within ahydraulic cylinder |18. At one end of the track l0 is a hydraulicallyoperated locking mechanism 20, and

at the other end oftrack l0 is a second hydraulically operated lockingmechanism 22. These mechanisms will be later specifically described, itbeing suiicient to say for the present that each comprises a cylinderhaving a hydraulically operated piston therein. The hydraulic system foroperating the locking mechanisms comprises hydraulic supply and returnlines 24 and 28 which connect a uid pump to a valve 28, from which line30 leads to hydraulic ther connected through line 32 to one end ofcylinder I8. Valve 28 is likewise connected to lock 22 through line 33,and line 33 is furtherjoined to the other end of cylinder I8 by line 34.

'I'his system operates as follows: When it is desired to raise the wheel2 from the down position shown, into the retracted position, valve 28 isturned so that fluid pressure ows through line 38. This fluid pressureenters the hydraulic mechanism and causes the lock tobe released oropened. At the same time, entered cylinder I8 through line 32 and assoon as the lock has been released, thepressure in cylinder I8 movespiston I6, which in turn causes arm I2 to be pulled to the left, thusmoving trolley 8 along track I0 and causing strut 6V to lift wheel 2 ina rotating movement about pivot 4. Trolley 8 moves across track I0 untilthe trolley 8 is en-gaged by the lockingmechanism 22.

When it is desired to lower wheel 2, the valve 28 is turned so thatpressure ows through line 33 into the hydraulic lock 22, the lock. Atthe same. time, fluid under pressure. enters cylinder I8 through line34, thus causing piston I6 to be moved to the right, and moving trolley8 to the right to lower wheel 2. A series system for operating thetrolley lock mechanism is shown in Fig. 2. Therein the wheel 2 is joinedto strut 6 and trolley 8, and the trolley is connected through arm I2 topiston I6 as in Fig. l. The locking mechanismsl'are,

however, of a differentconstruction. Thus, each having a piston movablewhich piston is movlock comprises a cylinder under iluid pressuretherein,

able to uncover an exhaust port, and thereby establishes, communicationbetween the intake and exhaust ports through the cylinder. Such acylinder is shown for example in Fig. 10, and it is to be understoodthat the cylinder can be used in either the trolley lock or strut lockmechanisms. Fluid pressure is again supplied through lines 24, 26 tovalve 28, and through line 30 to locking mechanism 36. This fluidpressure will move the piston to the right, thus releasing the lock uponthe trolley 8, and the piston moves until an exhaust port is uncoveredto establish communication between line 30 and line 38. Line 38 isjoined to one end of cylinder I8, and the iiuid pressure flowing throughlock 38 actuates piston I6 after the lock has been released. Piston I6functions as in Fig. l to move the trolley to the left until it engageslock 48. In the reverse operation. fluid pressure is communicated tolock 40 through line 33 from valve 28,-and the piston in lock 40 movesto the left to release the locking mechanism and to establishcommunication between the inlet line 33 and the exhaust line 42. Line 42is joined to the oppositey end of cylinder I8, and iluid pressureentering the cylinder from line 42 moves the piston I6 to cause thetrolley s to treve1 to the right. It is noted that a trigger lockmechanism, to be later described, holds eachlock open until lockingtakes place, and thus a reverse movement of operating fluid can takeplace through each cylinder.

The construction of the locking mechanism 28 is speccally illustratedand described in Figs. 3 and 4. A piston 58 is housed within cylinder52,

thereby releasing ieekzu. Line anisfurthe pressure has.

-ior the locking lug.

by spring 56, which bears against a nut 58 closing one end of thecylinder and locked thereto by wire 59. The other face of piston has aconnecting rod 60 extending therefrom. Packing 84 surrounding connectingrod 68 at the lefthand side of the cylinder is held in place by means ofa spring 62, the other end of which rests against a flange washer 66mounted in the cylinder wall. Packing material 68 provides a iiuid sealbetween the face of piston 58 and the cylinder wall, this packing beingheld in place by a spring metal retaining ring `IIJ resting againstshoulder 86. y

Cylinder 52 is extended-to form a housing 12 This housingis adapted tooverlie track I8 and to receive the trolley 8. 'I'he lacking lugcomprises a trigger a bell crank which has one end pivotallysecured tohousing 12 and'16. TheA bight of is pivotally connected to 'a link 18 at80, the other end of the link being pivotally joined to the end of rod.60 at 82. The free end 84 of trigger 14 is movable between abutments 86and 8B upon housing 12, and beneath which-trolley 8 slides. The uppersurface of the trolley, indicated in dot-dash lines in Fig. 4, has anotch 89 adapted to receive end 840i trigger 14.

A catch for latching trigger 14 in non-locking position, is provided bymeans of an arm 98 pivposition the upper Cil o tally mounted at 92 uponhousing 12. Arm 98 is normally urged by spring vIlllll to a position tothe left so that its edgeSIi abuts against an oblique edge 98 on plate88, note Fig. 5. YInthis end IUI of arm 90 engages within a recess onthe under surface of trigger 14 and holds trigger 14 so that the end 84cannot move downwardly. However, when arm 90 is struck by trolley 8, asindicated in Fig. 4, the arm is rotated to the right against thepressure of spring IML-and end IUI is moved back into a recess intrigger 14 so that end 84 of the trigger can fall downwardly intolocking engagement with the trolley. The operation of this device whenfluid pressure is applied through bore 54 is as follows:

Pieten 5o is moved to the rient against the Y shown in Fig, 5, so thatthe catch holds the triggerin upright position. This means that thetrigger cannot be lowered until arm 99 has been shifted by trolley 8,when the trolley is returned to its original position. In other words,the trigger 14 cannot fall to its locking position without the presenceof the trolley 8, so that Athe trolley can always be returned to itsfinal position corresponding either'to the fully retracted or to thefully extended position of the landing this cylinder being connectedthrough passage 54 with a source of uid pressure such as the line 30 inFig. 1.

Piston 50 is urged toward one end of cylinder 52 wheels. By these meansa portion of the operation ofthe hydraulic locking mechanism isdependent upon 'the function of the trolley. When the trolley engagesblade 90,'the trigger 14 is automatically moved to locking positionthrough the action of spring 56 against piston 50.

When this mechanism is used in the series circuit of Fig. 2, andincludes the special cylinder of the type shown in Fig. l0, the catchkeeps the piston in the cylinder in retracted position so thatcommunication between the inlet and exhaust ports exists through. thecylinder until 14 in the form of the crank Y inclusive.

N 9). As shown more clearly and connecting rods is substantially similarto that shown in Fig. 4. Mounted within cylinder |02`is a piston-|04, tooneend of which is joined a connecting rod |08. Piston IM'is urgedtoward the right by spring |08. Fluid is passed into cylinder |02through bore H0. Connecting rod |06 is joined to a trigger i2 through alink H4. Trigger H2 is substantially chevronshaped with one free endthereof pivotally mounted at IIS to the cylinder housing, the bight ofthe chevron being pivotally connected to link HB. The free end of thetrigger M2 is substantially triangular in shape' with a vertical edge|20 Yand an inclinedY edge |22.- Inclined edge |22Y presents a camsurface when struck by the trolley d, and under the cam action, triggerH2 is raised in order to allow the trolley to move to locked position.The trigger is lowered through action of spring |03 against piston itil.Otherwise, this unit functions according to the description given forthe operation oi Figs. 1 and 4.

The parallel or sexies connected hydraulic systems shown in Figs. 1 and2, respectively, can

-be adapted to operate the so-called strut-type locking mechanismsillustrated in Figs. 7 to 12, In Fig. 7, a wheel l2@ depends from strut|26, which is pivotally secured at |28 to the aircraft. Strut |20isprovided with an arm |29 at the upper end thereof and a lug |30adjacent wheel |210, each having a hole therethrough' which is adaptedto receive a pin from a hydraulically operated locking' mechanism soVthat the strut can be locked in lowered position by` means of arm- |29as illustrated in full lines of Fig. 7, 'or locked in up or retractedposition through lug |30 as illustrated in in Fig. 7. For purposes ofexample, locking mechanisms M for the down position, and |42 for the upposition, 'are indicated as being connected in paralleL-'as in Fig. Al,to the retracting mechanism. The .type of hydraulically operated lockingmechanisms i60, |42 which may be used, is more fully illustrated inFigs. 8 to 10. inclusive.

In Fig. 8, a piston |50 is-housed in cylinder |52, this pistonbeing-.provided with packing |56,

and being urged to the left by spring |55. To the other face .of thepiston is joined a locking pin |80. Fluid pressure is provided throughiitting |62, as from-.line 3'0, Fig. "1. Cylinder |52 is provided with ahousingA |64 into which in -the arm |29 or lugV |30 is adapted to enterand to be engaged by pin |06. -A trigger |66 having a iiange |61 ispivotally mounted upon a pin |68 within this housing and isurged bymeans of spring to a position which would normally prevent the end ofpin |60 fro'm entering the housing |64,.ange V|67 being adaptedto closeoff the path o'f'pin |60 (dotted line position Fig.

|26 is moved, either the lug |30 or arm |29 enters into housing IN ineither the up-or down' positions, respectively. of the landinggear asthe case may be, the lug' or arm engages trigger |66 and moves flange|61 out of the way so vthat pin lll can enter into the hole` provided,thus locking dotted lines in Fig. 9, when strut the left through Y beingprovided ment of pin 2id is limited nism cannot prevent the again beenpushed out of the way by lug or arm.

A hydraulically operated adapted to work with the series system shown inFig. 2, but for the strut locking mechanism shown in Fig. 7, isillustrated in Figs. 10 to 12. The

locking device to adapt them to series operation.

In Fig. 10, the hallowed-out piston 200 is housed within cylinder 202,the piston being urged. to the pressure of spring 204 and with metalrings 206 and packing 201. Fluid pressure is provided to the cylinder ofpiston 200 is a locking pin 2M. This pin is adapted ,to engage an `armor lug such as shown in Fig. '7.

Pin 2M is provided with 2| is rotatably journalled a recess 2|6. A shaftto thev cylinder housholds the pin 2| i in retracted position. When thearm or lug, Fig. 7. is to be locked to pin 2li, the strut engages camsurface 226 to rotate blade 220 and thus release the pin 2li, which,under the pressure of spring 204, is moved into locking engagement withthe arm or lug. Forward moveby engagement ofthe left-hand edge of piston200 with a stop plate 230 mounted on the interior wall of cylinder 202.As shown in Fig. 12, pin 2| d is also provided with a might turn recess2i6 away from blade 224.

` According to all of the forms of the invention, some means is providedlocking mechanism so that the locking mechalanding gear from being movedto the fully extended or fully retracted positionj Locking takes placeautomatically when the gear reaches the limit of its movement.

Having now described a means by which the objects of the invention maybe obtained,rwhat I claims as new and' desire to secure' by LettersPatent is:

1. In combination with a retractable landing Y gear for aircraftincluding a trolley movable ing adapted to the lug or arm inposition. Inreverseoperation,vv

removal of the pin and the trigger I of pin III so that along aV trackinto engagement with a locking mechanism, said mechanism comprising ahousreceive said trolley, trigger means mounted withinsaid housing forlocking engagement with said trolley, means for operating said triggermeans, and spring biased latch means actuatable by movement ofsaidtrolley for releasing said trigger from a latched non-lockingposition for movement into locking engagement space within the housinguntil trlgger I has with said trolley.

'2. In a landing gear,` a down lock, interconin conjunction with thenected hydraulic systems for retracting said landing gear and said downlock, said lock comprising a housing forming an abutment for a portionof a landing gear, a spring motor actuated pin mounted within saidhousing and adapted to engagesaid landing gear portion, said springmotor comprising a spring, a pin, a pistonfmeqnling-#cmdr1U nected tosaid pin ands'aid spring, said piston member forming a part of thehydraulic system for moving said pin out of engagement with said landinggear portion against a force exerted on said pin by saidrspring, and aVtrigger mechanism for holdingthe pin in the non-engaging position,Y fsaid trigger being actuated by said landing gear portion to release saidpin when said landing gear I portion is aligned with said housing toreceive said pin.

3. In a landing gear, a down lock, interconnected hydraulic systems forretracting said landing gear and said down lock, said lock compris- Iing a housing adapted to receive a portion of a landing. gear, a springmotor actuated latch pivotally connected to said housing and adapted toengage said landing gear portion, said spring motor comprising ahydraulic cylinder adjacent said housing and connected with a landinggear retracting mechanism, a piston member in said cylmeer for movingsaid latch vout disengagement Y with said landing gear portion, aconnecting rod pivotally joining said piston, through an intermediatelink, to said latch, a springv in said cylinder for moving said latchinto engagement with said-landing gear portion through said connecting'/f'rod and intermediate link, and a trigger mechafor locking engagementwith said lug, said mechansm comprising a housing adapted to receivesaid lug, a pin mounted within said housing and forming a part of saidlocking mechanism for locking engagement with said lug, means foroperatingsaid pin, and latch means actuatable by movement of said lugfor releasing said pin from a latched non-engaging vposition formovement 25 into locking engagement with said lug.

, JOHN `W. OVERBEKE.

